Norwegian Civil War

The Norwegian Civil War was a period of Norwegian history from 1130 to 1240 during which two dozen rival kings and pretenders laid claim to the throne of the Old Kingdom of Norway. The aristocratic, mercantile, and clerical Baglers fought against the peasant Birkebeiners, whose leader Haakon IV of Norway ultimately triumphed over the Bagler pretenders in 1240.

Background
In the late 1120s, during the reign of King Sigurd the Crusader of Norway, Harald Gille arrived from Ireland, claiming to be Sigurd's long-lost half-brother. Harald "proved" his claim by going through the Christian ordeal of fire, and Sigurd recognized Harald as his half-brother, although he forbade him from claiming the throne as long as he or his son, the future Magnus IV of Norway, were alive.

War of the impostors
When Sigurd died in 1130, Harald broke his oath, and he gained popular support for his claim to the throne. Peace was brokered when they agreed to be co-rulers, but, in 1134, open war broke out. In 1135, Harald defeated Magnus and captured him at Bergen, and he then had Magnus blinded, castrated, mutilated, and imprisoned in a monastery. At the same time, another impostor, Sigurd Slembe, claimed to be another half-brother, and he claimed to have gone through an ordeal of fire in Denmark to validate his claim. Harald did not recognize him as a brother, so Sigurd had Harald murdered in his sleep in 1136. Sigurd proclaimed himself king, but Harald's supporters instead named Harald's sons Sigurd Munn and Inge Crouchback named king. Sigurd Slembe liberated Magnus "the Blind" from his enforced monastic life and allied with him, and, in 1139, at the Battle of Holmengra, Magnus was killed and Sigurd was captured and tortured to death.

In 1142, Harald Gille's other son Oystein Haraldsson arrived in Norway and was given a third of the kingdom as a part of his father's inheritance, and he ruled in peace with Sigurd and Inge until 1155. Oystein and Sigurd Munn plotted to overthrow Inge and divide his lands between them, but Inge - at the urging of his mother Ingrid Ragnvaldsdotter, Inge struck first, killing Sigurd Munn before Oystein could arrive in Bergen, and then having Oystein murdered in 1157. The brothers' followers chose Sigurd Munn's son Haakon the Broadshouldered as their leader. In 1161, Inge was killed at the Battle of Oslo, and Inge's followers chose Magnus Erlingsson, the son of prominent nobleman Erling Skakke, as their pretender to the throne. In 1162, Haakon was killed in battle at Sekken, and Erling Skakke had another pretender, Sigurg Markusfostre, killed in 1163. In order to gain more support for Magnus, who was not the son of a king, his faction gained the support of the Catholic Church. That same year, a law was passed which only allowed for the oldest legitimate son to inherit the throne.

Rise of the Birkebeiners
In 1174, Eystein Meyla led a peasant rebellion against Magnus, and his followers became known as "Birkebeiners" due to the poorest of them being forced to wear birch-bark for shoes instead of proper footwear. Eystein was killed in battle at Re in 1177, but the Birkebeiners made Sverre their new leader. Sverre had only recently discovered that he was Sigurd Munn's son, and he came to Norway from the Faroe Islands to stake his claim. His men represented the impoverished strata of the population, but Sverre also quickly won over several nobles to his side. In 1179, at Kalvskinnet, Sverre defeated and killed Erling Skakke, and nearby Nidaros became Sverre's stronghold. King Magnus continued the fight even after his father's death, refusing to divide the kingdom, and Magnus was killed at the naval Battle of Fimreite in 1184; Sverre also killed the pretender Jon Kuvlung (Inge Crouchback's alleged son) at Bergen in 1188 and Sigurd Magnusson at the Battle of Florvag in 1194. Sverre ruled Norway until 1202, but the Church was virulently opposed to him throughout his reign; in 1198, Pope Innocent III placed Norway under interdict.

Rise of the Baglers
In 1197, Inge Crouchback's half-brother Bishop Nikolas Arnesson crowned Inge Magnusson as the figurehead king of Norway, and he was supported by the Baglers, a party which openly supported the Church. In 1202, Sverre died of disease, the first King of Norway to die of natural causes since Sigurd the Crusader in 1130. His son and heir Haakon III of Norway became the new Birkebeiner king, and he killed Inge that same year. He pacified the whole country, but his death in 1204 and the death of his infant Guttorm of Norway that same year led to the Birkebeiners choosing Inge Bardsson as their king, while the Baglers were revived in Denmark and chose Erling Steinvegg as their king. In 1204, the Baglers invaded Norway and took control of the Oslofjord area. In 1208, the two factions made peace, with the Bagler king Philip Simonsson ruling over eastern Norway without the title of King. In 1217, Inge died, so the Birkebeiners chose the young Haakon Haakonsson as their new king, while jarl Skule Bardsson, another claimant to the throne, commanded his army. Philip died that same year, and Skule persuaded the Baglers to swear fealty to Haakon. However, Erling Steinvegg's son Sigurd Ribbung led another rebellion which dragged on until 1227, when he died a natural death. In 1239, Skule Bardsson rose in rebellion, but his murder at a monastery in Nidaros in 1240 brought an end to the civil war and left Haakon and the Birkebeiners victorious.